Telephone-exchange system.



H. P. CLAUSEN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION HLED JAN. 2, 1918.

Patented Sept. 3, 1918,

LQ'Y'Z SGO HENRY P. CLAUSEN, OB MOUNT VERNON, NEW YORK, ASSIGNOR T0 WESTERN ELECTRTG OF NEW YORK, IN. I,

' cor/tram, INCORPORATED,

l 1 T @lFFlitC lrl A CORT-'ORATIGN OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

' Patented s t. a, rare.

To all whom it may concern:

Be it known that I, HENRY P. (known, a citizen of the United States, residing at Mount Vernon, in the county of Westchester, State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description. 1 a

This invention relates to telephone exchange systems and more particularly to such systems of the central energy type in which signaling current is automatically connected with a called-for telephone line.

An object of this invention is the provision of a system of this character employingimproved means for controlling the application of signaling current to the line.

In accordance with this invention, a link circuit employed in connecting together telephone lines is equipped with apparatus under the joint control of a listening key and the connection of the link circuit with a called-for telephone line for connecting therewith a source of signaling current. The link circuit is also equipped with apparatus controlled by a connected calling telephone line, whereby when a recall is made from the rent is automatically disconnected from the called-for line.

This invention will be more fully understood from the following description considered in connection with the accompanying drawing, illustrating one embodiment thereof.

In the drawing there are shown two telephone lines, A and B, terminating at a central office, at which is located a cord circuit C for interconnecting the line for conversation. It will be understood that many lines similar to lines A and B and a plurality of cord circuits similar to the cord circuit C, may be and are in practice usually provided, but, for convenience, onlythe two lines and the one cord circuit are shown. It is thought that the present invention will be best understood fromthe description of the operation of the system disclosed in the 7 drawing and it will be so described.

Subscriber A in initiating a call removes the receiver from the switchhook, causing the energization of line relay 5 and the lighting of line lamp '6. The operator observing the lighted condition of the lamp calling line, signaling curlay 9, th

-6, inserts calling plug 7 of the cord circuit G into line jack 8 of the calling line A. Relay 9 and cut-ofi' relay 10 thereupon operate. The operation of cut-0E relay 10 disconnects the line relay 5 from the line, thereby extinguishing the lamp 6. Relay 9 in operating closes the circuit of answering supervisory lamp 11, but the lamp is not, lighted, for as-soon as the plug 7 is inserted in the jack 8, supervisory relay 1-2 is operated over the line, thereby opening the circuit of the lamp 11. owever, since the contact of relay 9 is made before the normal contact of supervisory relay 12 is opened, relayv 15 is operated over a circuit from battery through the lower normal contact of listening key 16, the left-hand normal contact of the relay .15, thenormal contact of supervisory relay 12, and the contact of relay 9? to ground. Relay 15, in operating, connects an interrupter 17 through its righthand alternate contact to the alternate contact of supervisory relay 12, so that upon the energization of the supervisory relay 12, the lamp 11 is intermittently lighted to furnish to the operator a signal indicating that some act upon her part is required.

Relay 15, in operating, also establishes a locking circuit for itself through its lefthand normal contact and the contact of re ereby removing relay 15 from the control of the supervisory relay 12. The energization and locking up of relay 15 as described, presupposes that the listening key 16 is in its normal position when the plug 7 is inserted in the jack 8. If this key had been in its actuated condition, relay 15 would not then be operated. The actuation of the listening key connects the operators telephone set 18 with the talking strands of the cord circuit and opens the locking circuit of relay 15 which releases, stopping the intermittent lighting of the answering supervisory lamp 11.

Upon being'advisedthat the calling subscriber A desires to be connected with the line of subscriber B, the operator tests the called-for line (it being assumed that all of the lines are provided with multiple jacks) to determine diti'on of the line. Assuming the line to be idle, the calling plug 25 is inserted into line jack 26 and the listening key 16 is restored to normal position. Relay 27 and cut-ofi relay 28 are operated upon the inthe idle or busy conllll ll sertion of the plug 25 into the jack 26.

Relay '27, in operating, causes the lighting of calling supervisory lamp 24. The operation of relay 27 and the restoration of the listening key 16 to its normal position, connects ringing current to line B over a circuit from a source of ringing current 29 through the upper normal contact of listening key 16, right-hand normal contact of relay 15, winding of trip relay 30, righthand alternate contactof relay 27. upper normal contact of relay 31, tip contacts of the plug 25 and the jack 26, right-hand alternate contact of cut oft' relay 28, out over one side of line B, through the call bell 32 and condenser 33, back over the other side of the line, left-hand alternate contact of cut-off relay 28, ring contacts of the jack 26 and the plug 25, middle normal contact of relay 31, resistance 34, and battery to ground. The path by way of the resistance 34: is provided in shunt of the relay 27, so that there will be no tendency for the relay 27 to chatter while ringing current is connected with the line.

Subscriber B, in responding to the operation of the call bell 32; removes the receiver from its switchhook, thereby causing the operation of trip relay 30, removing a short circuit from the winding of relay 31. Relay 31 thereupon operates over a circuit from battery through the winding of relay 31,- resistance 35 and left-hand contact of relay 27 to ground.

Relay 31, in operating, opens another contact in the short circuit about its own winding, so that this short circuit cannot be reestablished when trip relay 30 releases its armature upon the opening of the upper normal contact of relay 31. Relay 31, in closing its alternate contact completes a circuit for supervisory relay 36, and in opening its middle normal contact removes the resistance 3 1 from shunt relation to the winding of relay 27. The talking circuit having been completed, the calling supervisory relay 36 is energized to extinguish the calling supervisory lamp 24..

At the conclusion of the conversation, the subscribers restore the receivers to the switchhooks, the restoration of subscriber Bs receiver to the switchhook causing the release of supervisory relay 36 and the light.- ing of the supervisory lamp 24 to furnish a disconnect signal. The restoration of the receiver to the switchhook by subscriber A, causes the release of supervisory relay 12 and the lighting of supervisory lamp 11 to furnish a disconnect signal. Relay 15 is also operated over the circuit hereinbefore described, and locks up. The operator may now withdraw the plugs from the jacks, whereupon all apparatus is restored to its normal condition.

lit, after the calling plug has been incircuit relation with the lamp 11.

serted in the line jack 26 and the ringing current is connected to line B, the calling subscriber A restores the receiver to the switchhook, the release of supervisory relay 12 causes the energization and locking up of relay 15 as already described. Relay 15, in operating, opens its right-hand normal contact which is included in the path of ringing current, thereby disconnecting ringing current from the called line. In this manner, whenever the calling subscriber restores the receiver to the switchhook after ringing current has been connected with the called line, the ringing current is auto matically disconnected therefrom. Should the calling subscriber. after having restored the receiver to the switchhook, immediately remove it therefrom to make a recall, this subsequent removal of the receiver from the switchhook before the plug 7 is withdrawn from the jack 8, causes the energization of the supervisory relay 12, whereupon the interrupter 17 is included in circuit with the answering supervisory lamp 11. This supervisory lamp is thereby intermittently lighted to furnish a recall signal. The operator, bserving such intermittent operation of the lamp 11, may actuate listening key 16 to connect the operators telephone set to the talking strands of the cord circuit. The actuation of the listening key 16 opens a contact in the locking circuit of relay 15, which thereupon releases its armatures, disconnecting the interrupter from While the relay 15, in releasing its arinatures, again closes its right-hand normal contact which is in the path of ringing current, ringing current is not thereby-reconnected to the called-for line, because this path for ringing current also includes the upper normal contact of listening key 16, which is open since the key is now actuated.

What is claimed is:

1. A telephone ex hange system comprising a telephone line, a link circuit, an operators telephone set, a listening switch controlling the connection and disconnection of the operators telephone setto and from the link circuit, electromagnetic switching means responsive to the connection of the link circuit with the telephone line, and a source of signaling current connected with the telephone line through contacts of the listening switch and the electromagnetic switching means.

2. A telephone exchange system compris ing a telephone line, a link circuit, an operators telephone set, a listening switch con trolling the connection and disconnection of the operators telephone set to and from the link circuit. a relay energized upon the connection of the link circuit with the telephone line, a source of sigi'ialing current, and circuit connections therefor including win 130 ing the source of signaling tact of the listening switch and an engaged contact of the energized relay for connectcurrent with the telephone line.

3. A tele 'ihone exchange system comprising a calling and a called telephone line, a link circuit connected with the calling telephone linc,a relay in the link circuit controlled from the calling telephone line, an operator's 'telephone set, a listening switch controlling the connection and disconnection of the operators telephone set to and from the link circuit, a relay energized upon the connection of the link circuit with the called line, a source of signaling current, and the circuit connections therefor including a con tact oi the. listening switch, a. contact of the relay controlled from the calling line, and engaged contacts of the energized relay for connecting the source of signaling current with the called telephone line.

4. A telephone exchange system comprising a calling and a called telephone line, a link circuit connected with the calling line, an operators telephone set, a listening switch controlling the connection and disconnection of the operators telephone set to and from the link circuit, a relay in the link circuit controlled from the calling line and by the listening switch, a relay energized upon the connection of the link circuit with the called line, and a source of signaling current connected with the called line through engaged contacts of the ener gized relay when the listening switch and the first mentioned relay are in their normal positions.

5. A telephone exchange system compris ing a calling and a called telephone line, a link circuit connected with the calling line,

an operator's telephone set, a listening switch controlling the connection and disconnection of the operators telephone set to and from the link circuit, a relay in the link circuit controlled from the calling line and by the listening switch, and a source of signaling current connected with the called line through normally closed contacts of the relay and the listenlng switch when the link circuit is connected with the called line. a

6. A telephone exchange system comprising a telephone line, a link circuit, an operators telephone set, a listening switch controlling the connection and disconnection of the operators telephone set to and from the link circuit, and a source of signaling current connected with the telephone line through a normally closed contact of the listening switch when the link circuit connected with the telephone line.

7. A telephone exchange system comprising a telephone line, a link circuit, an operator 's telephone set, a listening switch controlling the connection and disconnection of the operators telephone set to and from the link circuit, a source of signaling current whose connection with the telephone line is controlled by, the listening switch, a relay responsive to the connection of the link 7 circuit with the telephone line. and circuit connections established upon the response of the relay when the listening switch is in its normal positionover which current from the source of signaling current is connected with the telephone line.

In witness whereof, I hereunto subscribe my 7name this 28th day of December A. D., 191

HENRY P. CLAUSEN. 

